Forest
Service
Minnesota’s Forest
Resources in 2001
North Central
Research Station
Patrick D. Miles and Manfred E. Mielke
United States
Department of
Agriculture
Resource Bulletin
NC-217
North Central Research Station
U.S. Department of Agriculture - Forest Service
1992 Folwell Avenue
Saint Paul, Minnesota 55108
2003
www.ncrs.fs.fed.us
CONTENTS
Results ........................................................................................................... 1
Area ............................................................................................................ 1
Volume ....................................................................................................... 4
Biomass ..................................................................................................... 5
Forest Health .............................................................................................. 5
Appendix ...................................................................................................... 10
Inventory Methods ..................................................................................... 10
Sampling Phases ........................................................................................ 11
Phase 1 ...................................................................................................... 11
Phase 2 ...................................................................................................... 11
Literature Cited ........................................................................................... 13
Table Titles ................................................................................................... 13
Tables ........................................................................................................... 15
Minnesota’s Forest Resources
in 2001
The North Central Research Station’s Forest
Inventory and Analysis (NCFIA) program
began fieldwork for the sixth forest inventory of
Minnesota’s forest resources in 1999. This
inventory initiated the new annual inventory
system in which one-fifth of the field plots
(considered one panel) in the State are measured each year. A complete inventory consists
of measuring and compiling the data for all
plots (or five panels). Once all panels have been
measured, each will be remeasured approximately every 5 years. For example, in Minnesota, the field plots measured in 1999 will be
remeasured in 2004.
In 2001, NCFIA continued the annual inventory effort with the third panel of the sixth
forest inventory. Reports of previous inventories
of Minnesota are dated 1936, 1953, 1962,
1977, and 1990. This sixth inventory of
Minnesota’s forest resources will be completed
in 2003. However, because each year’s sample
is a systematic sample of the State’s forest and
because timely information is needed about
Minnesota’s forest resources, estimates have
been prepared from data gathered during the
first 3 years of the inventory. Data presented in
this report represent 60 percent of the field
plots (or three panels) for a complete inventory
and are a combination of the first year’s panel
from 1999, the second year’s panel from 2000,
and the third year’s panel from 2001. Earlier
reports for the 1999 panel (Schmidt 2000) and
the combined 1999 and 2000 panels (Haugen
et al. 2002) have also been published. Results
presented are estimates based on sampling
techniques; estimates were compiled assuming
the 1999, 2000, and 2001 data represent one
large sample. As additional annual inventories
are completed in years 4 and 5, the precision of
the estimates will increase and additional data
will be released.
Data from new inventories are often compared
with data from earlier inventories to determine
trends in forest resources. However, for the
comparisons to be valid, the procedures used in
the two inventories must be similar. As a result
of our ongoing efforts to improve the efficiency
and reliability of the inventory, several changes
in procedures and definitions have been made
since the last Minnesota inventory in 1990
(Miles et al. 1995) (see appendix). While these
changes will have little impact on statewide
estimates of forest area, timber volume, and tree
biomass, they may have significant impacts on
plot classification variables such as forest type
and stand-size class. Some of these changes
make it inappropriate to directly compare 2001
data tables with those published for 1990.
RESULTS
Area
The total land area of Minnesota is 50.9 million
acres of which 32 percent or 16.3 million acres
are forest land. There are three components to
forest land: (1) Timberland1—forest land that is
not restricted from harvesting by statute,
administrative regulation, or designation and is
capable of growing trees at a rate of 20 cubic
1
Timberland may not be equivalent to the area
actually available for commercial timber
harvesting or other access. The actual availability of land for various uses depends upon owner
decisions that consider economic, environment,
and social factors.
About the Authors:
Patrick D. Miles is a
research forester with
the Forest Inventory and
Analysis (FIA) unit at
the North Central
Research Station, St.
Paul, MN.
Manfred E. Mielke is
a plant pathologist with
the Forest Health
Protection program at
the St. Paul Field Office
of the Northeastern Area
State and Private
Forestry, St. Paul, MN.
Gary J. Brand is a
research forester with
the Forest Inventory and
Analysis (FIA) unit at
the North Central
Research Station, St.
Paul, MN.
feet per acre per year; (2) Reserved forest land—
land that is restricted from harvesting by statute,
administrative regulation, or designation (i.e.,
national parks, wilderness areas, etc.); and (3)
Other forest land—low-productivity forest land
that is not capable of growing trees at a rate of
20 cubic feet per acre per year.
The estimated area of forest land declined from
16.7 million acres in 1990 to 16.3 million acres
in 2001. During the same period, timberland
showed a slight increase from 14.7 million acres
in 1990 to 15.0 million acres in 2001 (fig. 1)2.
The decrease in forest land and the increase in
timberland are due in large part to changes in
the reserved and other forest land components.
The estimate of reserved forest land decreased
from 1,117 thousand acres in 1990 to 962
thousand acres in 2001, and the area estimate of
other forest land decreased from 840 thousand
acres to 349 thousand acres. Nearly half of this
acreage decrease in reserved and other forest
land was due to conversion to non-forest land
2
The error bars atop each bar in figure 1
provides a measure of reliability of these figures.
In 2001 there was a two out of three chance that
if a 100-percent inventory had been taken, using
the same methods, the result would have been
within the limits indicated by the bracket—
14,982.5 thousand acres plus or minus 128.9
thousand acres.
with the other half due to conversion to
timberland. The net effect was a decrease in the
area estimate for forest land and an increase in
the area estimate for timberland.
The estimate of timberland in public ownership
increased from 7.584 million acres in 1990 to
8.064 million acres in 2001 while private
ownership declined from 7.1392 million acres
to 6.9185 million acres over the same period
(fig. 2). Nearly four-fifths of all conifer forest
types are found on publicly owned land. Over
four-fifths of all private timberland is in the
hardwood forest types.
Changes in the plot design, stocking, and forest
typing algorithms limit comparisons of the 1990
and 2001 inventories. This is especially true
with plot classification variables such as forest
type and stand size. Whenever possible,
comparisons should be based on observed
variables such as tree species and diameter.
The aspen-birch forest type, with 6.7 million
acres of timberland, is the dominant forest type
in the State (fig. 3) and is an important resource
for Minnesota’s forest industries. Three-fourths
of all the coniferous timberland in the State is in
the spruce-fir forest type (3.1 million acres).
Between inventories, the estimate of hardwood
forest types increased from 10.2 million acres in
Figure 1.—Area of
timberland in
Minnesota by
inventory year.
Thousand acres
20,000
15,000
10,000
5,000
0
1936
1953
1962
1977
Inventory year
2
1990
2001
Ownership class
1990
2001
Private
Figure 2.—Area of
timberland in Minnesota by owner category.
Public
0
2,000
4,000
6,000
8,000
Thousand acres
1990
2001
Aspen/Birch
Forest type group
Maple/Beech/Birch
Figure 3.—Area of
timberland in
Minnesota in 1990
and 2001 by forest
type.
Elm/Ash/Cottonwood
Oak/Hickory
Spruce Fir
White/Red/Jack Pine
0
2,000
4,000
6,000
8,000
Thousand acres
3
1990 to 10.9 million acres in 2001, while the
estimate for conifer forest types decreased from
4.4 million acres in 1990 to 4.0 million acres in
2001. This appears to be the result of new
stocking and forest typing algorithms used in
conjunction with a new plot design rather than
a change in species composition because
roughly 31 percent of the State’s growing-stock
volume was in softwood tree species in both
1990 and 2001.
The area classified as small-diameter stands
(sapling/seedling stands where a plurality of the
stocking is in trees less than 5.0 inches at
diameter breast height (d.b.h.)) increased by 16
percent or by 701 thousand acres from 1990
(4,444.2 thousand acres) to 2001 (5,144.8
thousand acres). Most of this increase occurred
in the aspen-birch forest type where the area of
sapling/seedling stands is estimated to have
increased by 692 thousand acres. These changes
in area by stand-size class are due in part to
changes in the plot design and changes in the
stand-size classification algorithm (see Inventory Methods in the appendix).
The area classified as medium stands
(poletimber stands where a plurality of the
stocking is in trees from 5 to 9 inches d.b.h. for
conifers and 5 to 11 inches d.b.h. for hardwoods), rose from 5.3 million acres of timberland in 1990 to 5.7 million acres in 2001,
Large
Volume
Historically, volume has been reported as either
growing stock or sawtimber. However, there are
volumes in noncommercial trees, rough trees,
and rotten trees that do not qualify as growing
stock but that are utilized for wood fiber and
fuelwood. Such trees also make important
ecological contributions (such as for wildlife
habitat, and soil and water protection). With the
annualized inventory system and increased
interest in FIA data from an ecological perspective, a greater focus has been placed on all live
volume. In 2001, Minnesota had 17.4 billion
cubic feet of all live volume on its 16.3 million
acres of forest land. This equates to an average
of 1,068 cubic feet of all live volume for each
forest land acre in Minnesota. Unfortunately, all
live volume is not readily available from the
historic inventories and thus comparisons over
time consider only growing-stock volume.
Medium Small Nonstocked
9,000
8,000
Thousand acres
Figure 4.—Area of
timberland in Minnesota by stand-size
class and inventory
year.
despite an 8-percent decline in the number of
poletimber-size trees. Over the same period the
area classified as large stands (sawtimber stands
where a plurality of the stocking is in trees at
least 9.0 inches d.b.h. for conifers or 11.0
inches d.b.h. for deciduous trees) decreased by
17 percent (819 thousand acres) from 1990
(4,890.3 thousand acres) to 2001 (4,072.9
thousand acres), despite a 2-percent increase in
the number of sawtimber trees. Three-fifths of
this decrease occurred in the aspen-birch type.
7,000
6,000
5,000
4,000
3,000
2,000
1,000
0
1962
1977
Inventory year
4
1990
2001
Biomass
The net volume of growing stock on timberland
in Minnesota was estimated at 14.9 billion
cubic feet on 15.0 million acres in 2001, or 998
cubic feet of growing stock per acre (fig. 5).
The 1990 inventory estimates were 15.1 billion
cubic feet of growing stock on 14.7 million
acres of timberland, or 1,028 cubic feet of
growing stock per acre.
Biomass, measured as all live aboveground tree
biomass on timberlands, was estimated at 429
million dry tons in 2001 (an average of 29 dry
tons per acre). Biomass estimates are increasing
in importance for analyses on carbon sequestration, wood fiber availability for fuel, and other
issues. In 2001, 77 percent of the total biomass
was in growing-stock trees, an additional 14
percent was in trees less than 5 inches d.b.h.,
and the remaining 9 percent was in nongrowing-stock trees. Three-quarters of the total
biomass was composed of hardwood species.
Although total biomass was almost evenly split
on private (213 million dry tons) and public
(217 million dry tons) timberlands, softwoods
made up 34 percent of the total biomass on
public lands, but only 14 percent on private
lands.
The growing-stock volume of poletimber-size
trees decreased from 7.8 billion cubic feet in
1990 to 7.0 billion cubic feet in 2001, while
the growing-stock volume of sawtimber-size
trees increased from 7.4 billion cubic feet in
1990 to 8.0 billion cubic feet in 2001.
Hardwoods make up 69 percent of the
growing-stock volume and 65 percent of the
sawtimber volume in the State (fig. 6). In 2001,
the cottonwood-aspen species group accounted
for 39 percent of the hardwood volume,
followed by other eastern soft hardwoods (15
percent), ash (10 percent), basswood (8
percent), select white oaks (7 percent), select
red oaks (7 percent), soft maple (6 percent),
and hard maple (5 percent).
Forest Health
Staff of the Northeastern Area State and Private
Forestry Health Protection program, St. Paul
Field Office, provided the following forest
health information.
Insects, pathogens, weather events, fire, and
other factors cause damage and losses on forests
throughout Minnesota every year. Since 1954,
the eastern spruce budworm (Choristoneura
fumiferana) has defoliated spruce/fir forests
annually, establishing itself as the most consistently damaging agent in the State. However,
Softwood growing-stock volume was estimated
at 4.6 billion cubic feet in 2001. The spruce
and balsam fir species group accounted for 37
percent of the softwood volume, followed by
other eastern softwoods (31 percent), eastern
white and red pines (22 percent), and jack pine
(10 percent).
Softwoods
Hardwoods
All species
Million cubic feet
20,000
Figure 5.—Growingstock volume in
Minnesota by
inventory year.
15,000
10,000
5,000
0
1936
1953
1962
1977
1990
2001
Inventory year
5
Softwoods
Hardwoods
All species
45,000
40,000
Figure 6.—Sawtimber volume in
Minnesota by
inventory year.
Million board feet
35,000
30,000
25,000
20,000
15,000
10,000
5,000
0
1936
1953
1962
1977
1990
2001
Inventory year
since 1994, spruce budworm has been declining steadily (fig. 7). But as the budworm has
declined over that period, other damage agents
have stepped up their activity. Most notably the
forest tent caterpillar (Malacosoma disstria) has
been active throughout aspen and birch forests,
defoliating over 7.7 million acres in 2001 (table
10). Populations are expected to continue to be
at damaging levels in 2002. Other significant
damage agents that have been active during the
period between inventories are the large aspen
tortrix (Choristoneura conflictana) affecting the
aspen and birch forest types; the jack pine
budworm (Choristoneura pinus) defoliating and
killing older, open growing jack pine; and the
introduced larch casebearer (Coleophora
laricella), which has been increasing recently,
defoliating larch (table 10).
Since 1996, all of these and other defoliating
agents have been active, sometimes on some of
the same acreages at the same time. Trees that
are repeatedly defoliated often sustain measurable growth loss, which, in turn, sometimes
results in mortality. Figure 7 shows areas of the
State where, since 1997, forested lands have
been defoliated between one and five times.
6
Arguably, agents completely beyond human
control, namely the weather, cause the most
significant damage. Periods of drought and
flooding, snow, ice, cold, and wind damage are
an integral component of the State’s forest
dynamics. The single most significant event
occurred in 1999 when about 465,000 acres of
northern forests were blown down by straightline winds (fig. 8). This caused varying degrees
of breakage and mortality, which, in turn, has
had longer term impacts on subsequent insect
and pathogen activity and fire. The annual
current mortality resulting from all of these
damage agents, exceeding 10 percent of
standing trees, is displayed in figure 9. A more
complete discussion of forest health issues that
have affected Minnesota forests since the last
complete forest inventory, and current events is
available at: http://www.na.fs.fed.us/spfo/fhm/
fhh/fhh-01/mn/mn_01.htm.
For Further Information
Additional data related to the three most recent
inventories of Minnesota (1977, 1990, 2001)
are available at: http://www.ncrs.fs.fed.us/4801/
fiadb/index.htm.
Figure 7.—Areas of damage mapped by aerial survey, 1998-2001 (Forest Health Protection, St. Paul Field Office).
7
Figure 8.—Storm damage resulting from straight-line winds on July 4, 1999, includes mortality, broken, up-rooted and
still alive (Forest Health Protection, St. Paul Field Office).
8
Figure 9.—Areas of >10 percent mortality mapped by aerial survey, 1998-2001 (Forest Health Protection, St. Paul Field
Office) (1999 storm damage in northeast Minnesota was not included - see figure 8).
9
APPENDIX
Inventory Methods
Since the 1990 inventory of Minnesota, several
changes have been made in NCFIA inventory
methods to improve the quality of the inventory
as well as meet increasing demands for timely
forest resource information. The most significant change between inventories has been the
change from periodic inventories to annual
inventories. Historically, NCFIA periodically
inventoried each State on a cycle that averaged
about 13 years for recent inventories. However,
the need for timely and consistent data across
large geographical regions, combined with
national legislative mandates, resulted in
NCFIA’s implementation of an annual inventory
system. Minnesota was one of the first States in
the North Central region, and one of the first
States in the Nation, to be inventoried with this
new system, beginning with the 1999 panel of
measurements.
With an annual inventory system, about onefifth of all field plots are measured in any one
year. After 5 years, an entire inventory cycle will
be completed. After the first 5 years, NCFIA will
report and analyze results as a moving 5-year
average. For example, NCFIA will be able to
generate a report based on inventory results for
1999 through 2003 or for 2000 through 2004.
While there are great advantages for an annual
inventory, one difficulty is reporting on results
in the first 4 years. With the 2001 annual
measurements, only 60 percent of all field plots
have been measured. Sampling error estimates
for the 2001 inventory results are area of forest
land 0.86 percent, area of timberland 0.97
percent, number of growing-stock trees on
timberland 2.09 percent, volume of growing
stock on timberland 1.93 percent, and volume
of sawtimber on timberland 2.76 percent. These
sampling error estimates are considerably higher
than those for the last periodic inventory
completed in 1990 (i.e., 0.36 percent for
10
timberland area and 0.71 percent for growingstock volume) because of the smaller sample
sizes. Thus, caution should be used when
drawing conclusions based on this limited data
set. As we complete ensuing measurements, we
will have additional confidence in our results
due to the increased number of field plots
measured. As each measurement year is
completed, the precision of estimates will
improve.
Other significant changes between inventories
include the implementation of new remote
sensing technology, the implementation of a
new field plot design, and the gathering of
additional remotely sensed and field data. The
advent of remote sensing technology since the
previous inventory in 1990 has allowed NCFIA
to use computer-assisted classifications of
Multi-Resolution Land Characterization
(MRLC) data and other available remote sensing
products to stratify the total area of the State
and to improve estimates. Previous inventories
in Minnesota (1936, 1953, 1962, 1977, and
1990) used manual interpretation of aerial
photos to stratify the sample.
New algorithms were used in 1999-2001 to
assign forest type and stand-size class to each
condition observed on a plot. These algorithms
are being used nationwide by FIA to provide
consistency among States and will be used to
reassign the forest type and stand-size class of
every plot measured in the 1990 inventory
when it is updated. This will be done so that
changes in forest type and stand-size class will
more accurately reflect actual changes in the
forest and not changes in how values are
computed. The list of recognized forest types,
grouping of these forest types for reporting
purposes, equations used to assign stocking
values to individual trees, definition of
nonstocked, and names given to the forest types
changed with the new algorithms. As a result,
comparisons between the published 1999-2001
measurement results and those published for
the 1990 inventory results may not be valid.
For additional details regarding algorithms used
in both inventories, please contact NCFIA.
one of the above four strata. Stratification and
estimation were conducted at the State level for
national forest lands and at the FIA Inventory
Unit level for other lands. In the national forest
stratum, forest and forest-edge strata were
combined.
Sampling Phases
The 2001 Minnesota survey used a two-phase
sample for stratification that included
remeasuring inventory plots from the 1990
inventory and measuring new field plots. Twophase sampling, also called double sampling,
consists of a phase 1 sample to estimate area by
strata and a phase 2 sample to estimate the
average value of parameters of interest within
these strata. The estimated population total for
a parameter is the sum across all strata of the
product of each stratum’s estimated area and
the parameter’s estimated mean per unit area.
The only land that could not be sampled was
private land where field personnel could not
obtain permission from the owner to measure
the field plot and plots that could not be
accessed because of a hazard or danger to field
personnel. The methods used in the preparation of this report make the necessary adjustments to account for sites where access was
denied or hazardous. Fortunately, there were
only 23 denied access or hazardous plots in
1999, 60 in 2000, and 70 in 2001.
Phase 1
In this first phase the Minnesota inventory used
a computer-assisted classification of satellite
imagery. FIA used the imagery to form two
initial strata—forest and nonforest. Pixels
within 60 m (2 pixel widths) of a forestnonforest boundary formed two additional
strata—forest-edge and nonforest-edge. Forest
pixels within 60 m on the forest side of a forestnonforest boundary were classified into forestedge strata. Pixels within 60 m of the boundary
on the nonforest side were classified into
nonforest-edge strata. An overlay of all national
forest land was used to identify all lands owned
by national forests. These national forest lands
were treated separately but were also put into
Phase 2
Phase 2 of the inventory consisted of the
measurement of the annual sample of field plots
in Minnesota. Current FIA precision standards
for annual inventories require a sampling
intensity of one plot for approximately every
6,000 acres. FIA has established a grid that
divides the entire area of the United States into
non-overlapping hexagons, each of which
contains approximately 5,937 acres (McRoberts
1999). A grid of field plots was established by
selecting one plot from each hexagon based on
the following rules: (1) if a Forest Health
Monitoring (FHM) plot (Mangold 1998) fell
within a hexagon, it was selected as the grid
plot; (2) if no FHM plot fell within a hexagon,
the existing NCFIA plot from the 1990
inventory nearest the hexagon center was
selected as the grid plot; and (3) if neither FHM
nor existing NCFIA plots fell within the
hexagon, a new NCFIA plot was established in
the hexagon (McRoberts 1999). This grid of
plots is designated the Federal base sample and
is considered an equal probability sample; its
measurement in Minnesota is funded by the
Federal government.
The total Federal base sample was systematically divided into five interpenetrating, nonoverlapping subsamples or panels. Each year
the plots in a single panel are measured, and
panels are selected on a 5-year, rotating basis
(McRoberts 1999). For estimation purposes, the
measurement of each panel of plots may be
considered an independent systematic sample
of all land in a State. Field crews measure
vegetation on plots forested at the time of the
last inventory and on plots currently classified
as forest by trained photointerpreters using
aerial photos or digital ortho-quads.
11
NCFIA has two categories of field plot measurements—phase 2 field plots and phase 3
plots (FHM plots)—to optimize our ability to
collect data when available for measurement.
Both types of plot are systematically distributed
both geographically and temporally. Phase 3
plots are measured with the full suite of FHM
vegetative and health variables collected as well
as the full suite of measures associated with
phase 2 plots. Phase 3 plots must be measured
between June 1 and August 30 to accommodate
the additional measurement of non-woody
understory vegetation, ground cover, soils, and
other variables. We anticipate that in Minnesota
the complete 5-year annual inventory will
involve about 465 phase 3 plots. On the
remaining plots, referred to as phase 2 plots,
only variables that can be measured throughout
the entire year are collected. In Minnesota, the
complete 5-year annual inventory is expected
to involve about 5,200 phase 2 forested plots.
The 1999-2001 annual inventory results
represent field measures on 2,672 timberland,
217 other forest land, and 6,179 non-forest
land plots. The above number of field plots
represents a single intensification for the
standard base Federal sample in 1999 and a
double intensification for 2000 and 2001. This
double intensification was made possible by
additional resources provided by the State of
Minnesota.
The new national FIA 4-point cluster plot
design (fig. 10) was first used for data collection during the 1999 measurement of Minnesota. This design was also used in the 2000 and
2001 measurements and will be used in
subsequent years. The national plot design
requires mapping forest conditions on each
plot. Due to the small sample size (20 percent)
each year, precision associated with change
factors such as mortality will be relatively low.
Consequently, change estimates were not
reported in the 1999 or 2000 reports. Estimates
of change are reported for 2001 but are limited
in detail. When all five annual panels are
completed in 2004, the full range of change
data will be available.
12
2
N
1
4
Plot
center
MAGNETIC
3
Figure 10.—Current NCFIA field plot design.
The overall plot layout for the new design
consists of four subplots. The centers of
subplots 2, 3, and 4 are located 120 feet from
the center of subplot 1. The azimuths to
subplots 2, 3, and 4 are 0, 120, and 240
degrees, respectively. The center of the new plot
is located at the same point as the center of the
previous plot if a previous plot existed within
the sample unit. Trees with a d.b.h. of 5 inches
and larger are measured on a 24-foot-radius
(1/24 acre) circular subplot. All trees less than 5
inches d.b.h. are measured on a 6.8-foot-radius
(1/300 acre) circular microplot located 12 feet
east of the center of each of the four subplots.
Forest conditions that occur on any of the four
subplots are recorded. Factors that differentiate
forest conditions are changes in forest type,
stand-size class, land use, ownership, and
density. Each condition that occurs anywhere
on any of the subplots is identified, described,
and mapped if the area of the condition meets
or exceeds 1 acre in size and 120 feet in width.
Field plot measurements are combined with
phase 1 estimates in the compilation process
and table production. The number of tables
generated from less than five panels of data is
limited. However, as additional annual inventories are completed, the number of tables will
increase until year 5, when all statewide
inventory summary tables will be available in
both printed and electronic formats. For
additional information, contact:
Program Manager
Forest Inventory and Analysis
North Central Research Station
1992 Folwell Ave.
St. Paul, MN 55108
Or
State Forester
Division of Forestry
Minnesota Department of Natural Resources
P.O. Box 44, 500 Lafayette Road
St. Paul, MN 55155
LITERATURE CITED
Haugen, D.E.; Mielke, M.E. 2002.
Minnesota forest resources in 2000. Resour. Bull. NC-205. St.
Paul, MN: U.S. Department of Agriculture, Forest Service, North
Central Research Station. 26 p.
Mangold, R.D. 1998.
Forest health monitoring field methods guide (National 1998).
Research Triangle Park, NC: U.S. Department of Agriculture,
Forest Service, National Forest Health Monitoring Program.
429 p. (Revision 0, April 1998)
McRoberts, R.E. 1999.
Joint annual forest inventory and monitoring
system, the North Central perspective. Journal of
Forestry. 97(12): 27-31.
Miles, P.D.; Chen, C.M.; Leatherberry,
E.C. 1995.
Minnesota forest statistics, 1990, revised. Resour. Bull. NC158. St. Paul, MN: U.S. Department of Agriculture, Forest
Service, North Central Forest Experiment Station. 139 p.
Schmidt, T.L. 2001.
TABLE TITLES
Table 1.—Area of forest land by forest type group
and owner category, Minnesota, 1999-2001
Table 2.—Area of timberland by major forest type
group, stand origin, and owner category, Minnesota,
1999-2001
Table 3.—Area of timberland by forest type group
and stand-size class, Minnesota, 1999-2001
Table 4.—Net volume of all live trees on forest land
by species group and owner category, Minnesota,
1999-2001
Table 5.—Net volume of all live trees and salvable
dead trees on timberland by class of timber and
softwood/hardwood categories, Minnesota, 19992001
Table 6.—Net volume of growing stock on
timberland by forest group and softwood/hardwood
species categories, Minnesota, 1999-2001
Table 7.—Net volume of growing stock on
timberland by species group and diameter class,
Minnesota, 1999-2001
Table 8.—Net volume of sawtimber on timberland
by species group and diameter class, Minnesota,
1999-2001
Table 9.—All live aboveground tree biomass on
timberland by owner category, softwood/hardwood
species category, and tree biomass component,
Minnesota, 1999-2001
Table 10.—Area of forest land in Minnesota
affected by damage agents, 1994-2001
Minnesota’s forest resources in 1999. Res. Note RN-NC-376.
St. Paul, MN: U.S. Department of Agriculture, Forest Service,
North Central Research Station. 8 p.
13
TABLES
14
15
All forest types
9,264.3
16,293.7
---
7,029.4
-------
-----
Unidentified
owner
38.7
7.1
964.8
768.2
1,145.0
3,028.3
5,913.3
319.8
753.7
3.9
1,077.5
Private
All table cells without observations in the inventory sample are indicated by --. Table
value of 0.0 indicates the acres round to less than 0.1 thousand acres. Columns and
rows may not add to their total due to rounding.
75.8
114.4
723.1
2,865.2
-3,588.2
-309.8
515.2
673.3
4,102.0
5,600.3
Softwood type groups
White / red / jack pine group
Spruce / fir group
Exotic softwood group
All softwood types
Public
Owner category
7.1
1,274.6
1,283.3
1,818.3
7,130.3
11,513.6
1,042.9
3,618.9
3.9
4,665.7
Forest type group
Hardwood type groups
Oak / pine group
Oak / hickory group
Elm / ash / cottonwood group
Maple / beech / birch group
Aspen / birch group
All hardwood types
Nonstocked
All
owners
(In thousand acres)
Table 1. -- Area of forest land by forest type group and owner
category, Minnesota, 1999 - 2001
16
2,661.1
303.5
2,964.6
4,944.0
88.6
5,032.5
66.9
8,064.0
10,708.1
200.2
10,908.3
101.2
14,982.5
Public
---
6,918.5
----
----
Unidentified
owner
34.3
5,764.2
111.6
5,875.8
830.2
178.1
1,008.3
Private
Owner category
3,491.3
481.6
3,972.9
All
owners
All table cells without observations in the inventory sample are indicated by --. Table
value of 0.0 indicates the acres round to less than 0.1 thousand acres. Columns and
rows may not add to their totals due to rounding.
All groups
Softwood type groups
Natural
Planted
All softwood types
Hardwood type groups
Natural
Planted
All hardwood types
Nonstocked
Major forest type group
and stand origin
(In thousand acres)
Table 2. -- Area of timberland by major forest type group,
stand origin, and owner category, Minnesota, 1999 - 2001
17
---
-112.8
7.1
378.6
-753.6
7.1
10,908.3
101.2
14,982.5
All hardwood types
Nonstocked
864.1
3,267.5
-4,072.9
1,324.9
4,331.3
-5,663.6
2,680.6
677.9
587.0
3,309.6
-5,144.8
2,673.8
216.9
306.2
--
--
--
-101.2
101.2
All forest types
All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the acres round
to less than 0.1 thousand acres. Columns and rows may not add to their totals due to rounding.
1,758.9
6,679.3
Maple / beech / birch group
Aspen / birch group
1,245.0
1,218.0
Oak / hickory group
Elm / ash / cottonwood group
324.8
--
1,835.1
----
1,332.4
177.2
1,656.4
1.5
805.4
All softwood types
Hardwood type groups
Oak / pine group
318.5
1,013.8
--
3,972.9
Nonstocked
stocked
375.4
427.6
2.4
SaplingSaplingseedling
seedling
871.2
3,097.8
3.9
Poletimber
Poletimber
Softwood type groups
White / red / jack pine group
Spruce / fir group
Exotic softwood group
Sawtimber
Sawtimber
All
All
stands
stands
Stand-sizeclass
class
Stand-size
Forest
Forest type
type group
group
(In thousand acres)
Table 3. -- Area of timberland by forest type group and stand-size class, Minnesota, 1999 - 2001
18
17,397,433
All species groups
9,520,304
190,386
270,726
4,109
922
47,632
352,056
364,391
-452,707
2,608,520
304,794
292
1,048,615
696
8,582
5,654,430
-885,257
406,089
1,393,190
1,181,339
3,865,875
Public
7,877,128
743,984
569,263
93,688
30,034
13,559
318,896
418,087
-685,901
2,004,359
643,439
36,615
823,214
9,296
32,189
6,422,522
5,503
356,562
165,499
519,237
407,805
1,454,606
Private
Owner category
All table cells without observations in the inventory sample are indicated by --. Table
value of 0 indicates that the volume rounds to less than 1 thousand cubic feet. Columns
and rows may not add to their totals due to rounding.
934,370
839,989
97,798
30,956
61,191
670,951
782,478
-1,138,608
4,612,878
948,233
36,907
1,871,829
9,992
40,771
12,076,952
5,503
1,241,819
571,588
1,912,428
1,589,143
5,320,481
Hardwoods
Select white oaks
Select red oaks
Other red oaks
Hickory
Yellow birch
Hard maple
Soft maple
Beech
Ash
Cottonwood and aspen
Basswood
Black walnut
Other eastern soft hardwoods
Other eastern hard hardwoods
Eastern noncommercial hardwoods
Total hardwoods
Softwoods
Other yellow pines
Eastern white and red pines
Jack pine
Spruce and balsam fir
Other eastern softwoods
Total softwoods
Species group
All
owners
(In thousand cubic feet)
Table 4. -- Net volume of all live trees on forest land by species group and
owner category, Minnesota, 1999 - 2001
--
-----------------
-------
Unidentified
owner
19
57,179
64,952
122,131
4,858,139
162,696
322,189
16,474,387
11,616,248
97,744
200,058
102,313
29,383
169,496
1,083,943
11,416,191
140,112
914,447
226,035
688,413
4,905,529
10,332,247
1,469,505
5,426,719
3,957,214
Hardwood
species
All table cells without observations in the inventory sample are indicated by --. Table value of 0 indicates
that the volume rounds to less than 1 thousand cubic feet. Columns and rows may not add to their totals
due to rounding.
1 Includes noncommercial species.
All salvable dead trees
All classes
Poletimber size
Salvable dead trees
Sawtimber size
4,175
26,341
121,449
4,736,007
22,166
159,492
33,558
195,836
1,205,392
16,152,198
All live cull trees
All live trees
162,278
Sawtimber size
Poletimber size
Total
Rotten trees 1
95,109
31,033
257,068
Total
1,009,556
64,076
752,488
Sawtimber size
All growing-stock trees
Cull trees
Rough trees 1
Poletimber size
309,409
2,544,750
2,235,341
Softwood
species
2,069,808
4,614,558
1,778,914
7,971,469
6,192,555
All
species
6,975,337
14,946,806
Poletimber
Total
Upper stem portion
Live trees
Growing-stock trees
Sawtimber
Saw log portion
Class of timber
(In thousand cubic feet)
Table 5. -- Net volume of all live trees and salvable dead trees on timberland
by class of timber and softwood/hardwood categories, Minnesota, 1999 - 2001
20
All forest types
6,908
4,614,558
-53,855
145,949
153,268
992,209
1,345,281
1,127,126
2,131,147
4,097
3,262,370
Softwood
species
All table cells without observations in the inventory sample are indicated by --. Table
value of 0 indicates that the volume rounds to less than 1 thousand cubic feet. Columns
and rows may not add to their totals due to rounding.
10,048
14,946,806
-1,619,917
1,420,449
2,344,409
5,961,697
11,346,471
Hardwood type groups
Oak / pine group
Oak / hickory group
Elm / ash / cottonwood group
Maple / beech / birch group
Aspen / birch group
All hardwood types
Nonstocked
1,244,752
2,341,322
4,212
3,590,287
All
species
Softwood type groups
White / red / jack pine group
Spruce / fir group
Exotic softwood group
All softwood types
Forest type group
(In thousand cubic feet)
Table 6. -- Net volume of growing stock on timberland by forest group and
softwood/hardwood species categories, Minnesota, 1999 - 2001
3,140
10,332,247
-1,566,062
1,274,499
2,191,141
4,969,489
10,001,190
117,626
210,175
115
327,917
Hardwood
species
55,147
21,262
1,882
3,436
5,035
80,792
109,998
-175,673
476,894
60,439
987
255,540
2,476
1,001,594
4,614,558
773,519
756,812
67,727
30,593
48,379
542,237
623,456
-1,054,994
3,997,937
852,044
36,545
1,538,267
9,737
218
83,636
53,810
588,218
275,711
5.0-6.9
4,316
1,018,046
454,230
1,711,936
1,426,031
All
classes
79,380
54,080
4,394
4,825
4,888
108,700
131,728
-247,823
656,144
107,012
2,147
401,882
3,411
1,068,215
986
129,576
102,960
499,840
334,852
7.0-8.9
100,128
90,557
3,833
5,921
4,595
105,381
96,011
-213,579
719,535
134,520
6,763
367,520
1,209
869,358
1,707
137,526
128,266
316,372
285,487
9.0-10.9
102,084
132,494
9,996
9,059
3,704
75,006
77,695
-144,193
695,443
114,632
6,041
257,491
--
530,912
1,404
93,838
79,775
160,790
195,106
1,260,474
1,614,978
73,266
138,234
8,539
5,226
6,150
49,128
38,660
-105,562
586,873
119,004
2,808
126,100
926
354,504
-83,657
51,637
73,029
146,181
946,839
1,164,790
92,765
91,914
11,585
2,127
4,709
43,255
29,912
-73,543
404,824
98,538
10,885
81,068
1,713
217,951
-88,997
19,649
38,481
70,824
Diameter class (inches at breast height)
11.0-12.9
13.0-14.9
15.0-16.9
(In thousand cubic feet)
528,666
719,342
69,166
72,841
12,039
-7,272
30,790
20,420
-31,276
188,394
77,255
2,072
17,141
--
190,675
-102,856
12,662
17,112
58,046
17.0-18.9
Table 7. -- Net volume of growing stock on timberland by species group and diameter class, Minnesota, 1999 - 2001
10,332,247
1,249,561
1,627,838
1,806,415
1,849,552
14,946,806
2,251,155
2,874,630
2,718,911
2,158,750
All table cells without observations in the inventory sample are indicated by --. Table value of 0 indicates that the volume rounds
to less than 1 thousand cubic feet. Columns and rows may not add to their totals due to rounding.
Total hardwoods
All species
Hardwoods
Select white oaks
Select red oaks
Other red oaks
Hickory
Yellow birch
Hard maple
Soft maple
Beech
Ash
Cottonwood and aspen
Basswood
Black walnut
Other eastern soft hardwoods
Other eastern hard hardwoods
Total softwoods
Softwoods
Other yellow pines
Eastern white and red pines
Jack pine
Spruce and balsam fir
Other eastern softwoods
Species group
21
350,438
478,025
39,153
77,995
3,675
-5,035
9,723
14,784
-28,704
86,538
73,574
-11,259
--
127,587
-95,411
5,472
6,708
19,996
19.0-20.9
547,609
767,613
119,714
60,253
11,783
-6,990
39,462
61,534
-29,111
147,285
46,368
4,841
20,267
--
220,004
-168,791
-11,384
39,828
21.0-28.9
164,854
198,613
42,718
17,182
----42,715
-5,530
36,008
20,702
----
33,759
-33,759
----
29.0+
22
15,039
4,341,164
1,473,284
3,212,374
4,250,889
13,292,750
All
classes
8,176
682,841
611,214
1,585,904
1,440,741
4,328,877
9.0-10.9
6,863
471,085
392,035
824,988
1,000,587
2,695,558
11.0-12.9
-431,368
264,658
386,424
766,336
1,848,786
-474,114
104,952
211,040
380,648
1,170,754
325,960
344,663
57,323
-36,863
149,262
96,729
152,442
914,826
376,433
10,139
79,260
-2,543,900
3,593,149
-562,855
69,490
97,346
319,558
1,049,249
Diameter class (inches at breast height)
13.0-14.9
15.0-16.9
17.0-18.9
1
2,506,213
-320,117
422,993
418,492
2,694,420
-605,664
421,816
542,340
267,887
-37,946
53,242
41,782
65,190
-21,553
9,249
34,388
168,470
-29,135
23,040
16,579
1,137,821
-220,514
203,604
314,819
1,336,456
-169,963
137,682
316,821
1,932,586
-485,777
350,381
622,219
9,835,056
-2,671,791
1,916,639
2,963,287
2,590,124
-541,373
466,398
489,733
126,703
-13,263
52,425
26,152
2,212,465
-554,244
368,873
1,056,213
11,661
-4,015
7,646
--6,842,827
24,885,053
5,675,353
4,433,988
38,177,803
4,328,877
9,538,385
7,524,139
5,604,742
All table cells without observations in the inventory sample are indicated by --. Table value of 0 indicates that the volume rounds
to less than 1 thousand board feet. Columns and rows may not add to their totals due to rounding.
1 International 1/4-inch rule.
Hardwoods
Select white oaks
Select red oaks
Other red oaks
Hickory
Yellow birch
Hard maple
Soft maple
Ash
Cottonwood and aspen
Basswood
Black walnut
Other eastern soft hardwoods
Other eastern hard hardwoods
Total hardwoods
All species
Softwoods
Other yellow pines
Eastern white and red pines
Jack pine
Spruce and balsam fir
Other eastern softwoods
Total softwoods
Species group
(In thousand board feet)
-537,628
30,934
38,727
112,718
720,007
19.0-20.9
189,300
381,096
18,228
-26,022
48,184
72,269
142,494
427,801
365,966
-53,614
-1,724,975
2,444,982
Table 8. -- Net volume of sawtimber on timberland by species group and diameter class, Minnesota, 1999 - 2001
602,045
306,546
59,366
-36,831
201,438
311,973
149,489
745,242
238,826
24,724
100,261
-2,776,742
4,053,269
-978,280
-67,946
230,300
1,276,526
21.0-28.9
227,307
92,295
----231,019
29,784
195,470
111,395
---887,269
1,090,262
-202,993
---202,993
29.0+
23
105,057,147
324,312,777
429,369,924
212,631,051
20,393,202
41,320,258
61,713,460
21,012,421
25,812,260
4,799,839
20,307,837
35,901,200
15,593,363
All live
1-5 inch trees
81,771,289
247,541,571
329,312,859
163,249,040
138,574,191
24,674,849
166,063,820
108,967,380
57,096,440
Total
Tree biomass component
62,715,989
179,638,495
242,354,485
100,499,234
119,637,080
19,137,846
79,139,261
122,717,404
43,578,143
Boles
19,055,299
67,903,075
86,958,375
38,074,957
43,611,959
5,537,002
29,828,118
43,346,415
13,518,297
Stumps, tops,
and limbs
Growing-stock trees
2,029,747
Total
862,910
2,892,656
35,450,948
38,343,604
22,706,841
23,569,751
2,206,016
26,308,656
28,514,672
16,806,561
17,462,740
656,179
9,502,095
11,051,932
1,549,836
Boles
686,641
9,142,292
9,828,932
5,900,280
6,107,011
206,730
3,242,011
3,721,921
479,910
Stumps, tops,
and limbs
Non-growing-stock trees
12,744,107
14,773,853
All table cells without observations in the inventory sample are indicated by --. Table value of 0 indicates the aboveground tree
biomass rounds to less than 1 dry ton. Columns and rows may not add to their totals due to rounding.
All ownerships
Softwoods
Hardwoods
Total
Total
30,337,597
182,293,454
Hardwoods
216,738,873
Private
Softwoods
Total
74,719,550
142,019,323
Hardwoods
All
components
Public
Softwoods
Owner category and
softwood/hardwood
category
(In dry tons)
Table 9. -- All live aboveground tree biomass on timberland by owner category,
softwood/hardwood species category, and tree biomass component, Minnesota, 1999 - 2001
24
7,759,807
-17,909
18,893
2,300
-18,816
16,800
1,052
2,122
2,424
-----47,358
7,887,481
2001
2,039,919
63,942
30,697
28,481
20,000
7,507
6,363
6,061
365
100
------20,571
2,224,006
2000
495,000
340,000
-70,000
-------465,000
920
150,000
--7,614
1,528,534
1999
1
Aerial survey results 1994-2001
All table cells without observations in the inventory sample are indicated by --.
Forest tent caterpillar
Large aspen tortrix
Flooding
Spruce budworm
Oak tatters
Frost
Larch casebearer
Oak mortality
Dutch elm disease
Bark beetles
Winter injury
Wind/Tornado
Walking stick
Oak anthracnose
Aspen defoliator complex
Jack pine budworm
Mortality
Total acres effected
Minnesota damage agents
1998
1997
(In acres )
9,000
2,064
9,000
---240,242 257,000
------------------------5,776
10,308
264,018 269,372
---207,727
-----------74,836
-282,563
1996
Table 10.-- Area of forestland in Minnesota effected by damage agents 1994-2001 1
1994
9,120
-----500,100 2,704,000
--------------217,800
-----36,600
599,627
66,501
6,900
--830,121 3,310,527
1995
The U.S. Department of Agriculture (USDA) prohibits discrimination
in all its programs and activities on the basis of race, color, national
origin, gender, religion, age, disability, political beliefs, sexual
orientation, and marital or family status. (Not all prohibited bases
apply to all programs.) Persons with disabilities who require
alternative means for communication of program information (Braille,
large print, audiotape, etc.) should contact USDA’s TARGET Center at
(202) 720-2600 (voice and TDD).
To file a complaint of discrimination, write USDA, Director, Office of
Civil Rights, Room 326-W, Whitten Building, 14th and Independence
Avenue, SW, Washington, DC 20250-9410, or call (202) 720-5964
(voice or TDD). USDA is an equal opportunity provider and employer.
The Forest and Analysis web site is:
www.fia.fs.fed.us
Printed on recyclable paper.
Miles, Patrick D.; Mielke, Manfred E.; Brand, Gary J.
2003. Minnesota’s forest resources in 2001. Resour. Bull. NC-217. St. Paul,
MN: U.S. Department of Agricultue, Forest Service, North Central Research
Station. 24 p.
Results of the combined 1999, 2000, and 2001 annual forest inventories
of Minnesota show that 16.3 million acres or 32 percent of the total land
area is forested. The estimate of total all live tree volume on forest land is
17.4 billion cubic feet or approximately 1,068 cubic feet per acre. Nearly 15.0
million acres of forest land in Minnesota are classified as timberland (forest
land that is not reserved and is of high productivity). The estimate of growing-stock volume on timberland is 14.9 billion cubic feet or approximately
998 cubic feet per acre. All live aboveground tree biomass on timberland is
estimated at 429 million dry tons or approximately 28.7 tons per acre.
Important pests in Minnesota forests include the forest tent caterpillar,
spruce budworm, large aspen tortrix, and introduced larch casebearer.
KEY WORDS: Annual inventory, forest area, forest type, volume, biomass,
Minnesota
Mission Statement
We believe the good life has its roots in clean air, sparkling water, rich soil, healthy
economies and a diverse living landscape. Maintaining the good life for
generations to come begins with everyday choices about natural resources. The
North Central Research Station provides the knowledge and the tools to help
people make informed choices. That’s how the science we do enhances the
quality of people’s lives.
For further information contact:
North Central
Research Station
USDA Forest Service
1992 Folwell Ave., St. Paul, MN 55108
Or visit our web site:
www.ncrs.fs.fed.us